CDM Registers
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 5-15
NOTE
The clock ratio should only be changed if no module, which is clocked by the IPB and/or PCI clock,
is currently running. Suggestion is to change the clock ratio during the boot time only.
5.5.5 CDM 48MHz Fractional Divider Configuration Register—MBAR + 0x0210
The CDM 48MHz Fractional Divider Configuration Register contains the control bits used in the 48MHz fractional divider.
Bit Name Description
0–6 Reser ved for future use. Write 0.
7 ddr_mode SDRAM Controller DDR memor y mode, read-only.
bit=0 :SDRAM Controller configured for SDR SDRAM (single data rate)
bit=1 :SDRAM Controller configured for DDR SDRAM (double data rate)
This register location is a read-only status bit; write 0. The controlling register is in the
SDRAM Controller register map. In the CDM this bit determines the frequency and phase
of memory read clock.
8–14 Reserved for future use. Write 0.
15 xlb_clk_sel XLB Clock Frequency
bit=0 :XLB CLK = fsystem /4
bit=1 :XLB CLK = fsystem /8
This register location is a read-only status bit. The controlling register is the POR
Configuration register - cdm configuration register [26].
16–22 Reserved for future use. Write 0.
23 ipb_clk_sel IPB Clock Select
bit=0 :IPB CLK = XLB_CLK
bit=1 :IPB CLK = XLB_CLK/ 2
24–29 Reserved for future use. Write 0.
30-31 pci_clk_sel PCI Clock Select
00–PCI_CLK = IPB_CLK
01–PCI_CLK = IPB_CLK/2
10–PCI_CLK = XLB_CLK /4
See also Tab le 5-3 and Tabl e 5-4.

Table5-12. CDM 48MHz Fractional Divider Configuration Register

msb 0123456789101112131415
RReserved
Write 0
ext_usb_
sync_en
ext_usb_
48mhz_en
ext_irda_
48mhz_en
Reserved
Write 0
fd_en
W
RESET: 0 0 0 0000000000000
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 lsb
R
Rsrvd
Write 0
cfgd_p3_cnt
Rsrvd
Write 0
cfgd_p2_cntt
Rsrvd
Write 0
cfgd_p1_cnt
Rsrvd
Write 0
cfgd_p0_cnt
W
RESET: 0 0 0 0000000000000